Before proceeding on introducing bitcoin into those old people, you should know first if they are interested. If it looks like they are not interested, then you do not have to continue teaching it into them. Not old people are open on new technologies or new blockchains such as bitcoin, but there's also some that are exciting to know about it.

I guess if someone plans to start introducing or teaching it into them, he/she already know what bitcoin is, does not necessary to be much, enough is enough. They won't understand bitcoin if they are not interested in the first place.